Spyware/adware is a category of malicious computer code that is a growing nuisance and a threat to the privacy of computer users.
Spyware is software that persists itself in an unusual or an obnoxious way on the user's computer. The computer does not know that the spyware is present. The user did not give permission to the spyware to reside on the user's computer. The spyware may be difficult to uninstall, even manually. It tries to mask its presence as it extracts something from the user's computer. The item that is extracted might be relatively innocuous, such as a marketing preference, or something very important, such as the user's credit card number.
Adware may visibly display a pop-up ad on the user's computer, or it may simulate clicks from the user to obtain revenue for an advertiser. Adware can range from quasi-legitimate to deceitful.
Regardless of the particular definitions that are employed, this category of malicious computer code is an increasing menace and must be thwarted, while minimizing the rate of false-positive declarations of spyware/adware.